植物抗病相关启动子及其研究进展

启动子是调控基因表达的重要顺式元件。植物抗病相关启动子的调控特性研究、分离及其应用对于提高植物抗病性极其关键。本文综述了植物基因启动子的基本结构、克隆方法,着重介绍了组成型、组织特异型、天然与人工合成的病原诱导型启动子的研究进展,及其在植物抗病基因工程中的应用现状和存在问题,并展望了植物抗病相关启动子的应用前景。     

A Novel Pyrimidin-Like Plant Activator Stimulates Plant Disease Resistance and Promotes Growth

Plant activators are chemicals that induce plant defense responses to a broad spectrum of pathogens. Here, we identified a new potential plant activator, 5-(cyclopropylmethyl)-6-methyl-2-(2-pyridyl)pyrimidin-4-ol, named PPA (pyrimidin-type plant activator). Compared with benzothiadiazole S-methyl ester (BTH), a functional analog of salicylic acid (SA), PPA was fully soluble in water and increased fresh weight of rice (Oryza sativa) and Arabidopsis plants at low concentrations. In addition, PPA also promoted lateral root development. Microarray data and real-time PCR revealed that PPA-treated leaves not challenged with pathogen showed up-regulation of genes related to reactive oxygen species (ROS), defenses and SA. During bacterial infection, Arabidopsis plants pretreated with PPA showed dramatically decreased disease symptoms and an earlier and stronger ROS burst, compared with plants pretreated with BTH. Microscopy revealed that H₂O₂ accumulated in the cytosol, plasma membrane and cell wall around intracellular bacteria, and also on the bacterial cell wall, indicating that H₂O₂ was directly involved in killing bacteria. The increase in ROS-related gene expression also supported this observation. Our results indicate that PPA enhances plant defenses against pathogen invasion through the plant redox system, and as a water-soluble compound that can promote plant growth, has broad potential applications in agriculture.     

Lack of Specificity in Plant Extracts and Chemicals as Inducers of Systemic Resistance in Cucumber Plants to Anthracnose

Canoia, lettuce, green bean, dwarf pea, tobacco, tomato, poplar, corn, wheat, and cucumber leaves were extracted by boiling with 95% ethanol. The ethanol was removed from the ethanol-water extract, and the water-soluble fraction was centrifuged and filtered to remove compounds with a molecular weight > 1 000 D. The undersides of the first true leaf of a cucumber plant (leaf 1) and the leaf above (leaf 2) were sprayed with each plant extract (induction), and 7 days later leaf 3 was inoculated with a conidial suspension of Colletotrichym lagenarium (challenge). Extracts from all plants tested induced systemic resistance in leaf 3 to C. lagenarium . Commercially available compounds were screened to determine structural similarities among the compounds which can induce systemic resistance. All compounds which induced resistance in leaf 3 caused some damage to leaves 1 and 2. but not all compounds which damaged leaves 1 and 2 induced resistance in leaf 3. Galacturonic acid, glucuronic acid, salicyhc acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, y-resorcylic acid, protocatecbuic acid, gallic acid, hemimelletic acid, trimelletic acid, trimesic acid, phloroglucinol, and glycine induced systemic resistance, whereas catechol, resorcinol, hydroquinone, pyrogaLol, hydroxyhydroquinone, benzoic acid, phthalic acid, α-resorcylic acid, β-resorcylic acid, gentisic acid. 2, 3-dihydroxybenzoic acid, benzaldehyde, 2,3-dihydroxybenzaldehyde, β-resorcaldehyde, protocatechuic aldehyde, benzyl alcohol, salicyl alcohol, myo-inositol, phytic acid, pinitol, and quebrachitol did not. Structural similarities were not evident among either compounds which induced systemic resistance or those that did not.     

Repraesentins D,E and F,New Plant Growth Promoters from Lactarius repraesentaneus

Three new plant growth regulatory sesquiterpenes were isolated from the Lactarius repraesentaneus fungus. Their structures were elucidated to be lactarane sesquiterpenes, namely repraesentins D (1) and E (2), and a protoilludane-related sesquiterpene, namely repraesentin F (3). Repraesentin E (2) showed the strongest promotion activity, 164% at 3.6 μM, of the three compounds toward the radicle elongation of lettuce seedlings.     

Differential Influence of Ectomycorrhizae on Plant Growth and Disease Resistance in Pinus sylvestris Seedlings

The influence of Laccaria laccata, Hebeloma crustuliniforme, and Pisolithus tinctorius mycorrhizae and a mixture of naturally occurring mycorrhizae on the resistance of Pinus sylvestris seedlings to attack by Fusarium moniliforme and Rhizoctonia solani was investigated periodically during an entire year under greenhouse conditions following inoculation with both mycobiont and pathogen. Using artificial root substrate the seedlings were provided with a balanced butlow nutrient supply. Seedling growth (dry weight) as well as short-root formation was stimulated to different extents depending on the mycobiont species; in addition, the degree of stimulation varied over the year. Parasitized plants were more stimulated, than nonparasitized ones. Disease severity and plant mortality caused by either pathogen were drastically reduced in the presence of the mycorrhizal fungi, even before mycorrhiza formation. All mycorrhizae, except the association with Hebeloma, remained highly protective throughout the year; with Hebeloma it remained protective for only about 3 months. Growth stimulation or mycorrhiza frequency was not always correlated with the level of protection; e.g. Hebeloma protected withoutstimulating growth. Two types of protection apparently exist, one related to and another unrelated to growth stimulation. Mycorrhizal fungi had little or no antagonistic effects on fungal pathogens in vitro.     

Antimicrobial Resistance in Scandinavia after a Ban of Antimicrobial Growth Promoters

The banned use of antimicrobial growth promoters resulted in a considerably decreased use of antimicrobials in food animal production in Sweden (65%), Denmark (47%), Norway (40%) and Finland (27%). The current prevalence of antimicrobial resistance in animal bacterial populations is also considerably lower than in some other countries in the EU. In the swine production, no or limited effect was found in the finisher production (>25 to 30 kg). Temporary negative effects occurred during the post weaning period (7–30 kg). In Denmark, the cost of production from birth to slaughter per pig produced increased by approximately 1.0 [euro]with a high variability between pig producers. In the broiler production the termination had no significant negative effect on animal health and welfare or on production economy.     

植物抗病反应的信号传导网络

植物由抗病基因介导的防卫过程存在一系列生理生化和分子生物学反应,这些反应从病原菌侵染点开始的超敏反应(HR)并延伸到远处组织的系统抗性或获得性抗性(SAR),受制于一种信号传导网络的调控。这个信号系统由抗病蛋白和病原菌非毒性蛋白在一种配体-受体的互作模式下激发,并由信号分子H2O2,NO和系统信号分子SA,JA和乙烯和通过关键调控基因传递和放大,最终诱导一系列防卫反应基因的表达和代谢的变化而产生抗性。植物防卫信号的产生有类似于动物免疫系统因子的介导,并可由非寄主病原菌或诱导子诱发。这些信号途径所产生的广谱抗性为植物抗病基因工程的应用奠定了基础。     

植物生长物质与植物抗旱性的关系(综述)

脱落酸、乙烯、多胺和细胞分裂素等是与植物抗旱性关系较为密切的几种植物激素。文章就植物在遭受干旱胁迫时其体内激素变化及喷施植物生长调节剂对植物抗旱性的影响进行概述,为生化调控植物抗旱性提供参考。     

植物抗病基因的进化

植物抗病基因在进化中形成了几种共有的进化形式。植物祖先抗病基因的复制创造了新基因座。基因间和基因内重组导致了变异,也导致了新特异性抗病基因的产生。另外,与特异性识别相关的富含亮氨酸重复区顺应于适应性选择。同样,类转座元件在抗病基因座中的插入加速了抗病基因的进化。随着抗病基因的进化,抗病反应也呈现出多样化,代表着植物与病原物动态进化的不同阶段。     

Somatic Embryogenesis in Sugarcane (Saccharum officinarum L.): Growth and Plant Regeneration from Embryogenic Cell Suspension Cultures

Embryogenic cell suspension cultures were established from calliderived from young leaves of sugarcane (Saccharum officinarumL.) by placing them in liquid medium containing 5 per cent coconutwater (CW), 2–3 mg 1^–1 2, 4-D and 500 mg 1^–1casein hydrolysate (CH). The cultures were maintained by transferring2.5–5.0 ml of the suspension to 35 ml of fresh mediumevery 4–5 days. Organized structures resembling the earlystages of embryogeny were formed when 2, 4-D in the medium waslowered (0.1–1.0 mg 1^–1) but these did not developbeyond the globular or early scutellar stages. High levels ofsucrose (6–10 per cent) promoted the formation of proembryoids.Plating of the suspension on MS agar medium supplemented with0.25–2.0 mg 1^–1 2, 4-D, 5 per cent CW, 500 mg 1^–1CH, with or without activated charcoal, resulted in the formationof embryogenic calli. A large number of embryoids were formedin media containing lower 2, 4-D concentrations. Transfer ofembryoids to half-strength MS medium with 6 per cent sucroseestablished plantlets which were successfully transferred tosoil. Saccharum officinarumL, sugarcane, suspension culture, embryogenesis, regeneration     

NLR及其在植物抗病中的调控作用

为适应丰富多变的生存环境, 植物逐渐进化出一套复杂的免疫系统来抵抗病原菌的侵染。核苷酸结合的富含亮氨酸重复蛋白(NLR)作为植物体内普遍存在的一类抗性(R)蛋白, 对植物的抗病性具有重要调控作用。该文综述了NLR蛋白结构、信号转导以及对植物抗病的调控作用近几年的研究进展。     

Biostimulants Derived from Moroccan Seaweeds: Seed Germination Metabolomics and Growth Promotion of Tomato Plant

Polysaccharides extracted from seaweeds can function as plant biostimulants. The aim of this study was to assess the effects of Polysaccharide Enriched Extracts (PEEs) obtained from 17 Moroccan seaweeds, on tomato seed germination and plant growth. Three concentrations (0.02, 0.05 and 0.1 mg mL⁻¹) of PEEs were applied to tomato seeds to evaluate their effect on 3 germination parameters: germination percentage (GP), germination speed (GS) and mean germination time (MGT). Metabolomic analysis by GC–MS was subsequently performed on seedlings. In the second experiment, four PEEs concentrations (0.02, 0.05, 0.1 and 0.2 mg mL⁻¹) were used as foliar spray or as soil application to tomato plants. Their growth parameters (number of leaves, shoot length, fresh and dry weight of stem and roots) and biochemical parameters (chlorophyll a and b) were measured. Results indicated a significant increase of GP and GS associated with a significant reduction of MGT of tomato seeds treated with 0.02 mg mL⁻¹ of PEEs obtained from Gigartina sp., Gigartina pistillata, Chondracanthus acicularis, Gelidium crinale, Schizymenia dubyi, Cystoseira. foeniculacea and Fucus spiralis. Similar results were also obtained by application of higher PEEs concentration (0.1 mg mL⁻¹) extracted from Ulva rigida, Codium tomentosum, Codium decorticatum and Bifurcaria bifurcata. Metabolomic analysis on seedlings detected the presence of some metabolites which could possibly be involved in seed germination enhancement or inhibition. The results of the second experiment showed that the same PEEs cited above at the same concentrations enhanced plant dry weight and chlorophyll a content except Gigartina sp., C. foeniculacea and C. decorticatum. Furthermore, soil application of PEEs was more effective in improving plant growth parameters than foliar application. The study shows the potential of PEEs from Moroccan seaweed to be used as biostimulants for a sustainable agriculture.

     

植物糖基转移酶在植物抗病过程中的研究进展

植物在复杂的环境中进化出了各种反应来应对危害,其中糖基化作用就是植物利用的一种主要的生理机制.糖基化作用通过改变受体化合物的生物活性及其细胞内的定位来降低外物质对自身的影响,从而达到植物体生理代谢的稳态.植物中的糖基转移酶就是专门负责实现这种糖基化反应的酶类.简要概述了糖基转移酶在植物抗性过程中的研究方法、分类及生物学功能,并对其研究方向加以展望.     

小G蛋白在植物抗病性中的作用(英文)

小G蛋白一类是低分子量GTP结合蛋白,其分子量大约20～30 kDa。小G蛋白作为重要的分子开关参与了细胞许多重要生理信号途径的调控。近几年在植物中的研究、尤其是对模式植物水稻抗病分子机制的研究发现,Rho家族的小G蛋白在植物抗病信号传导途径的调控中起了关键的作用。本文对植物特有的Rho家族小G蛋白在植物免疫反应中的最新研究进展进行了综述。     

诱导植物抗病的几种化合物及其抗病机理

介绍了近年来发现的几种能够诱导植物产生抗病反应的化合物,这些化合物包括β氨基丁酸、龙胆酸以及油菜素类固醇,并进一步探讨了这些化合物诱导植物抗病的不同机理。